newb connection

<?php

    class Database {

        public function __construct() {

            /*** hostname ***/
            $hostname = '$config[db][host]';
            /*** dbname ***/
            $dbname = '$config[db][dbname]';
            /*** username ***/
            $username = '$config[db][username]';
            /*** password ***/
            $password = '$config[db][password]';

            function dbcon ($hostname, $username, $password){
                $dbh = new PDO("mysql:host=$hostname;dbname=$dbname", $username, $password);
                $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
            }

            try {
                $dbh = dbcon ($hostname, $username, $password);
            } catch(PDOException $e) {
                echo $e->getMessage();
            }

        }
    }